Bio-resorbable polymer stents: a review of material progress and prospects

Abstract

Coronary Artery Disease (CAD) remains the leading cause of death in the developed world. The advent of drug-eluting Bio-resorbable Stents (BRSs) heralded a significant development in the field of CAD, representing a step-change in the treatment paradigm and offering significant improvements in patient outcome. But, as noted by a Task Force sanctioned by the European Commission in 2017, their widespread clinical deployment has primarily been hampered by a lack of randomised clinical trial data demonstrating improved efficacy over traditional permanent drug-eluting stents (DESs). To date, only the Abbott BVS, voluntarily withdrawn from sale in 2017, has undergone such rigorous evaluation, and which showed inferior outcomes at 2–3 years. This timely review paper addresses leading BRS polymer stent technologies to highlight the trends in design strategies and current technological advancements aimed at overcoming such performance limitations. This review examines the leading BRS technologies to gauge the progression of polymer materials technology and strategies in this field. To highlight emerging trends with respect to constituent materials, the developmental history of each stent is discussed briefly, providing context to progress. Many stent features that relate to material selection including material types, material combinations, drugs, architecture features, strut thickness, processing techniques and radiopacity are considered and compared. Following detailed review of these stents, materials and related features are summarised and discussed to highlight the changing clinical needs, current targets and challenges ahead.